Disentangling effects of climate and land use on biodiversity and ecosystem services – a multi-scale experimental design

1. Climate and land-use change are key drivers of environmental
degradation in the Anthropocene, but too little is known about their
interactive effects on biodiversity and ecosystem services. Long-term data
on biodiversity trends are currently lacking. Furthermore, previous
ecological studies have rarely considered climate and land use in a joint
design, did not achieve variable independence or lost statistical power by
not covering the full range of environmental gradients. 2. Here, we
introduce a multi-scale space-for-time study design to disentangle effects
of climate and land use on biodiversity and ecosystem services. The site
selection approach coupled extensive GIS-based exploration and correlation
heatmaps with a crossed and nested design covering regional, landscape and
local scales. Its implementation in Bavaria (Germany) resulted in a set of
study plots that maximize the potential range and independence of
environmental variables at different spatial scales.
3. Stratifying the state of Bavaria into five climate zones
(reference period 1981–2010) and three prevailing land-use types, i.e.
near-natural, agriculture and urban, resulted in 60 study regions (5.8x5.8
km quadrants) covering a mean annual temperature gradient of 5.6–9.8 °C
and a spatial extent of ~310x310 km. Within these regions, we nested 180
study plots located in contrasting local land-use types, i.e. forests,
grasslands, arable land or settlement (local climate gradient 4.5–10 °C).
This approach achieved low correlations between climate and land use
(proportional cover) at the regional and landscape scale with |r≤0.33| and
|r≤0.29|, respectively. Furthermore, using correlation heatmaps for local
plot selection reduced potentially confounding relationships between
landscape composition and configuration for plots located in forests,
arable land and settlements. 4. The suggested design expands upon
previous research in covering a significant range of environmental
gradients and including a diversity of dominant land-use types at
different scales within different climatic contexts. It allows independent
assessment of the relative contribution of multi-scale climate and land
use on biodiversity and ecosystem services. Understanding potential
interdependencies among global change drivers is essential to develop
effective restoration and mitigation strategies against biodiversity
decline, especially in expectation of future climatic changes.
Importantly, this study also provides a baseline for long-term ecological
monitoring programs.